The present invention relates to a slip-controlled brake system, in particular for motor vehicles, having a hydraulic power booster and a master cylinder arranged downstream of the power booster, wherein the pressure chamber of the power booster can be acted upon by an external pressure depending on the position of a pedal-actuatable brake value, and wherein an auxiliary cylinder, for example a fast-fill cylinder, is provided which can be acted upon by the dynamic pressure and through which additional pressure fluid can be supplied to the brake circuits of the master cylinder.
Known multiple-circuit brake systems operate according to the principle of dynamic flow into a brake circuit wherein the dynamic pressure corresponds to the pressure acting upon the hydraulic booster piston. These systems suffer from the shortcoming that in the event of a failure of the circuit both the boosting effect and the braking effect of the circuit will be lost.
In addition, brake systems have already been proposed, such as that disclosed in the published German application No. P 35 07 484.1 which are provided with a pedal-actuated brake power booster which is connected to the master cylinder and which comprises a booster piston and a booster chamber, wherein an auxiliary pressure proportional to the pedal force is generated by way of a brake valve. Such brake systems are equipped with a fast-fill cylinder provided with a stepped bore wherein a two-step piston is displaceably arranged. A pressure chamber is provided in front of the large step of the two-step piston and a pressure chamber is provided in front of the small step. In this case, the pressure chamber is connected to the booster chamber and the filling chamber to the working chamber of the master cylinder. A non-return valve is inserted into a connecting line connecting the booster chamber with the pressure chamber of the fast-fill cylinder, and the control gate of the brake valve cooperates with a valve body through which the brake valve communicates with the pressure chamber. This known brake system, however, requires a relatively large installation space since the fast-fill cylinder is designed as an additional separate unit.